Sex-related differences in the processing and experience of pain at the beginning of life

Background: This study explores sex differences in neonatal pain perception, an area that remains relatively understudied despite well-documented disparities in adult pain experiences. The research aims to identify sex-related patterns in neonatal pain responses using both behavioural and neurophysiological data, obtained employing the Neonatal Infant Pain Scale (NIPS) and near-infrared spectroscopy (NIRS).

Methods: A secondary analysis was conducted on previously published data of our research group, collected from 100 healthy full-term newborns (48 males, 52 females) undergoing a routine heel-prick for metabolic screening. Participants to the original studies were randomly allocated to one of the following non-pharmacological pain relief methods: oral glucose solution, expressed breast milk, maternal holding with glucose administration, breastfeeding, or maternal holding alone.

Results: It was observed that female newborns exhibited a significantly more pronounced behavioural response to pain compared to their male counterparts (p = 0.031), with this difference being particularly evident during breastfeeding as an analgesic intervention (p = 0.10). Female newborns also showed an increased activation of the left somatosensory cortex in response to heel-prick (p = 0.029). During breastfeeding analgesia, this difference involved the right somatosensory cortex too (p = 0.010).

Conclusions: These findings underscore the importance of incorporating sex-specific considerations in neonatal pain assessment and management protocols. The study suggests that developing tailored, sex-specific approaches may be crucial for ensuring optimal pain care in newborns, potentially leading to more effective and personalized neonatal care strategies. In the end, this research contributes to the growing body of evidence supporting the need for sex-specific considerations for pain management since early-life.

Dr. Stefano Bembich is a clinical psychologist and researcher. Currently, he works at the University Hospital of Udine (Italy), in the Mother-Child Department, as clinician. In collaboration with the Institute for Maternal and Child Health IRCCS “Burlo Garofolo” of Trieste (Italy), his research activity concerns the application of cerebral near-infrared spectroscopy, as a functional neuroimaging technique, in the field of neonatology. He published more than 20 papers on this topic.